Dolphins are incredible — so incredible that researchers copied their skin in hopes of saving some dollars and reducing CO2 emissions. Photos: Unsplash
Nature is pretty cool. Evolution has slowly but surely influenced the creation of some incredible things; things that we humans are routinely copying in the interests of speed, strength, or any manner of qualities that we haven’t quite figured out how to optimize in our short time on Earth. The latest aping from the wisest of the Great Apes? A new boat propeller with a coating that mimics dolphin skin.
According to reports, the screw coating, which was made by the Ningbo Institute of Materials Technology and Engineering (NIMTE), could “significantly reduce fuel consumption and emissions in large cargo ships.”
As I mentioned, using nature’s creations in our own is nothing new. Hell, even surfers do it. Remember Kelly Slater’s Great White Twin? That was a surfboard shaped after the body outline of a shark. Dolphins in particular have been the models for many of our inventions. Watching a dolphin swim, after all, can feel almost meditative. What’s strange, though, is that dolphins really shouldn’t be able to swim how they do.
Since dolphins actually do have quite a bit of drag and their muscles, pound-for-pound, were thought to be about as strong as an average high-level human athlete, researchers were confounded for decades about how, exactly, they reached the speeds they do. For years, they studied them, even giving the problem a name.
In 1936, zoologist Sir James Gray noticed that dolphins could swim faster than 20 mph without the apparent strength do it. That strange conundrum confused researchers for decades. Gray’s Paradox stated that “the drag power experienced by a dolphin was larger than the estimated muscle power.” Gray, at the time, theorized that the likely reason had something to do with a dolphin’s skin possessing some kind of strange drag-reducing quality. But in 2008, nearly 75 years later, researchers armed with cutting-edge flow measurement technology came up with an answer. And it wasn’t the skin: it was just that dolphins are way freaking stronger than Gray knew.
Still, though, Gray’s theory wasn’t crazy. As we’ve looked closer at dolphin skin, it is indeed special. According to Blue Voice, an ocean conservation organization founded in 2000 by Hardy Jones and Ted Danson, “the entire surface of a dolphin’s skin is covered by microfolds which direct the water flow and minimize turbulence as it swims.”
Nature is pretty cool, right? Not only did it make the dolphin immensely strong, but it gave it skin that cuts through water like a hot knife through warm butter. That nearly frictionless flow of water over a dolphin’s skin is called laminar flow. Anyway, now that the history lesson is done, back to the propeller.
Laminar flow is common both in watercraft and aircraft. It reduces drag, which increases speed. Since more drag and friction require more fuel, ship and airplane designers are constantly looking for ways to reduce drag as much as possible.
NIMTE simply (not all that simply) applied that same principle to ship propellers. The coating on the props isn’t exactly like dolphin skin — that would be nearly impossible — but it’s based on it.
Researchers from Ningbo Institute of Materials Technology and Engineering partnered up with COSCO Shipping Energy Transportation Co., Ltd to try and figure out a way to save the shipping giant a few bucks on fuel. Inspired by dolphins and sharks and the way they’re able to move so easily through the ocean, they did their best to make something that might act in a similar manner when sprayed onto a propeller. Using artificial synthesis, they came up with something “composed of liquid-like dynamic interfacial materials and flexible materials between 0.1 and 0.2 mm microstructure.”
Researchers estimate that covering a cargo ship-sized propeller would cost around $20,000 USD, which might sound like a lot until you consider the fact that over a 200-day test run that covered a little over 35,000 nautical miles, the dolphin skin propellers saved an average of two percent on fuel costs. That works out to be roughly $140,000 in fuel costs over the course of a year. And not only is that good for the bottom line, it’s good for the planet, too. That much unburned fuel keeps about 900 tons of CO2 emissions out of the atmosphere in a time when we really, really need to be figuring out ways to curb our emissions.
